Bone treatment systems and methods

ABSTRACT

Systems and methods for treating vertebral compression fractures are discussed. In an embodiment, a method includes mixing bone cement precursors thereby causing a first chemical curing reaction characterized by a first time-viscosity profile, controllably applying energy to the bone cement from an external source to modify the first time-viscosity profile to a second time-viscosity profile, and injecting the cement into bone at a substantially constant viscosity greater than about 1000 Pa·s to greater than about 5000 Pa·s over an extended working time. In another embodiment, a bone cement injector system is provided that includes a first handle component that is detachably coupled to a second sleeve component having a distal end for positioning in bone and a flow channel extending through the first and second components. The system includes first and second thermal energy emitters for delivering energy to bone cement flows in a flow channel portion in the first and second components, respectively.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. §119(e)of U.S. Provisional Application No. 61/009,699, filed on Dec. 31, 2007,entitled Bone Treatment Systems And Methods; No. 61/009,659, filed onDec. 31, 2007, entitled Bone Treatment Systems And Methods; No.61/009,671, filed on Dec. 31, 2007, entitled Bone Treatment Systems AndMethods; and No. 61/009,673, filed on Dec. 31, 2007, entitled BoneTreatment Systems And Methods, the entirety of which are herebyincorporated by reference and should be considered a part of thisspecification.

This application is further related to the following U.S. patentapplication Ser. No. 11/209,035 filed Aug. 22, 2005, titled BoneTreatment Systems and Methods; Provisional Application No.60/842,805filed Sep. 7, 2006 titled Bone Treatment Systems and Methods;No. 60/713,521filed Sep. 1, 2005 titled Bone Treatment Systems andMethods; No. 60/929,936filed Apr. 30, 2007 titled Bone Treatment Systemsand Methods and No. 60/899,487filed Feb. 5, 2007 titled Bone TreatmentSystems and Methods. The entire contents of all of the aboveapplications are hereby incorporated by reference and should beconsidered a part of this specification.

BACKGROUND

1. Field of the Invention

Embodiments of the present disclosure relate to bone cement injectionsystems, and, in certain embodiments, provide systems and methods foron-demand control of bone cement viscosity for treating vertebralcompression fractures and for preventing cement extravasation.

2. Description of the Related Art

Osteoporotic fractures are prevalent in the elderly, with an annualestimate of 1.5 million fractures in the United States alone. Theseinclude 750,000 vertebral compression fractures (VCFs) and 250,000 hipfractures. The annual cost of osteoporotic fractures in the UnitedStates has been estimated at $13.8 billion. The prevalence of VCFs inwomen age 50 and older has been estimated at about 26%. The prevalenceincreases with age, reaching approximately 40% among 80-year-old women.Medical advances aimed at slowing or arresting bone loss from aging havenot provided solutions to this problem. Further, the population affectedwill grow steadily as life expectancy increases. Osteoporosis affectsthe entire skeleton but most commonly causes fractures in the spine andhip. Spinal or vertebral fractures also cause other serious sideeffects, with patients suffering from loss of height, deformity andpersistent pain which can significantly impair mobility and quality oflife. Fracture pain usually lasts 4 to 6 weeks, with intense pain at thefracture site. Chronic pain often occurs when one vertebral level isgreatly collapsed or multiple levels are collapsed.

Postmenopausal women are predisposed to fractures, such as in thevertebrae, due to a decrease in bone mineral density that accompaniespostmenopausal osteoporosis. Osteoporosis is a pathologic state thatliterally means “porous bones”. Skeletal bones are made up of a thickcortical shell and a strong inner meshwork, or cancellous bone, withcollagen, calcium salts, and other minerals. Cancellous bone is similarto a honeycomb, with blood vessels and bone marrow in the spaces.Osteoporosis describes a condition of decreased bone mass that leads tofragile bones which are at an increased risk for fractures. In anosteoporosis bone, the sponge-like cancellous bone has pores or voidsthat increase in dimension making the bone very fragile. In young,healthy bone tissue, bone breakdown occurs continually as the result ofosteoclast activity, but the breakdown is balanced by new bone formationby osteoblasts. In an elderly patient, bone resorption can surpass boneformation thus resulting in deterioration of bone density. Osteoporosisoccurs largely without symptoms until a fracture occurs.

Vertebroplasty and kyphoplasty are recently developed techniques fortreating vertebral compression fractures. Percutaneous vertebroplastywas first reported by a French group in 1987 for the treatment ofpainful hemangiomas. In the 1990's, percutaneous vertebroplasty wasextended to indications including osteoporotic vertebral compressionfractures, traumatic compression fractures, and painful vertebralmetastasis. Vertebroplasty is the percutaneous injection of PMMA(polymethyl methacrylate) into a fractured vertebral body via a trocarand cannula. The targeted vertebra is identified under fluoroscopy. Aneedle is introduced into the vertebral body under fluoroscopic control,to allow direct visualization. A bilateral transpedicular (through thepedicle of the vertebra) approach is typical but the procedure can bedone unilaterally. The bilateral transpedicular approach allows for moreuniform PMMA infill of the vertebra.

In a bilateral approach, approximately 1 to 4 ml of PMMA is used on eachside of the vertebra. Since the PMMA needs to be forced into thecancellous bone, the techniques require high pressures and fairly lowviscosity cement. Since the cortical bone of the targeted vertebra mayhave a recent fracture, there is also the potential for PMMA leakage.The PMMA cement contains radiopaque materials so that, when injectedunder live fluoroscopy, cement localization and leakage can be observed.The visualization of PMMA injection and extravasation are critical tothe technique, enabling the physician to terminate PMMA injection whenleakage is evident. The cement is injected using syringes to allow thephysician manual control of injection pressure.

Kyphoplasty is a modification of percutaneous vertebroplasty.Kyphoplasty involves a preliminary step including the percutaneousplacement of an inflatable balloon tamp in the vertebral body. Inflationof the balloon creates a cavity in the bone prior to cement injection.The proponents of percutaneous kyphoplasty have suggested that highpressure balloon-tamp inflation can at least partially restore vertebralbody height. In kyphoplasty, some physicians state that PMMA can beinjected at a lower pressure into the collapsed vertebra since a cavityexists, when compared to conventional vertebroplasty.

The principal indications for any form of vertebroplasty areosteoporotic vertebral collapse with debilitating pain. Radiography andcomputed tomography are performed in the days preceding treatment todetermine the extent of vertebral collapse, the presence of epidural orforaminal stenosis caused by bone fragment retropulsion, the presence ofcortical destruction or fracture and the visibility and degree ofinvolvement of the pedicles.

Leakage of PMMA during vertebroplasty can result in very seriouscomplications, including compression of adjacent structures that maynecessitate emergency decompressive surgery. See “Anatomical andPathological Considerations in Percutaneous Vertebroplasty andKyphoplasty: A Reappraisal of the Vertebral Venous System”, Groen, R. etal, Spine Vol. 29, No. 13, pp 1465-1471 2004. Leakage or extravasationof PMMA is a critical issue and can be divided into paravertebralleakage, venous infiltration, epidural leakage, and intradiscal leakage.The exothermic reaction of PMMA carries potential catastrophicconsequences if thermal damage extends to the dural sac, cord, and nerveroots. Surgical evacuation of leaked cement in the spinal canal has beenreported. It has been found that leakage of PMMA is related to variousclinical factors such as the vertebral compression pattern, the extentof the cortical fracture, bone mineral density, the interval from injuryto operation, the amount of PMMA injected, and the location of theinjector tip. In one recent study, close to 50% of vertebroplasty casesresulted in leakage of PMMA from the vertebral bodies. See Hyun-Woo Doet al, “The Analysis of Polymethylmethacrylate Leakage afterVertebroplasty for Vertebral Body Compression Fractures”, J. of KoreanNeurosurg. Soc. Vol. 35, No. 5 (5/2004) pp. 478-82.

Another recent study was directed to the incidence of new VCFs adjacentto the vertebral bodies that were initially treated. Vertebroplastypatients often return with new pain caused by a new vertebral bodyfracture. Leakage of cement into an adjacent disc space duringvertebroplasty increases the risk of a new fracture of adjacentvertebral bodies. See Am. J. Neuroradiol. 2004 February; 25(2):175-80.The study found that about 58% of vertebral bodies adjacent to a discwith cement leakage fractured during the follow-up period compared withabout 12% of vertebral bodies adjacent to a disc without cement leakage.

Another life-threatening complication of vertebroplasty is pulmonaryembolism. See Bernhard, J. et al, “Asymptomatic diffuse pulmonaryembolism caused by acrylic cement: an unusual complication ofpercutaneous vertebroplasty”, Ann. Rheum. Dis. 2003; 62:85-86. Thevapors from PMMA preparation and injection also are cause for concern.See Kirby, B, et al., “Acute bronchospasm due to exposure topolymethylmethacrylate vapors during percutaneous vertebroplasty”, Am.J. Roentgenol. 2003; 180:543-544.

In both higher pressure cement injection (vertebroplasty) andballoon-tamped cementing procedures (kyphoplasty), the methods do notprovide for well controlled augmentation of vertebral body height. Thedirect injection of bone cement simply follows the path of leastresistance within the fractured bone. The expansion of a balloon appliesalso compacting forces along lines of least resistance in the collapsedcancellous bone. Thus, the reduction of a vertebral compression fractureis not optimized or controlled in high pressure balloons as forces ofballoon expansion occur in multiple directions.

In a kyphoplasty procedure, the physician often uses very high pressures(e.g., up to about 200 or 300 psi) to inflate the balloon, which maycrush and compact cancellous bone. Expansion of the balloon under highpressures close to cortical bone can also fracture the cortical bone,typically the endplates, which can cause regional damage to the corticalbone with the risk of cortical bone necrosis. Such cortical bone damageis highly undesirable as the endplate and adjacent structures providenutrients for the disc.

Kyphoplasty also does not provide a distraction mechanism capable of100% vertebral height restoration. Further, the kyphoplasty balloonsunder very high pressure typically apply forces to vertebral endplateswithin a central region of the cortical bone that may be weak, ratherthan distributing forces over the endplate.

SUMMARY OF THE INVENTION

Certain embodiments of the invention provide bone cement injectors andcontrol systems that allow for vertebroplasty procedures that injectcement having a substantially constant viscosity over an extended cementinjection interval.

A computer controller is provided to control cement flow parameters inthe injector and energy delivery parameters for selectively acceleratingpolymerization of bone cement before the cement contacts the patient'sbody.

In accordance with one embodiment, a bone treatment system is provided.The system comprises a bone fill material injector system comprising aninjector configured to be at least partially introduced into a bone. Thesystem also comprises a thermal energy emitter operatively coupled tothe injector system and configured for delivering energy to a flow ofbone fill material through the injector system. An electronic controlleris configured to modulate the delivery of energy from the thermal energyemitter to the flow of bone fill material based at least in part on asensed pressure in the injector system to achieve a desired bone fillmaterial viscosity.

In accordance with another embodiment, a method for treating bone isprovided. The method comprises flowing bone fill material through a bonefill material injector system having at least a portion of an injectorpositioned in a cancellous bone portion of the bone, delivering energyto the flow of bone fill material via a thermal energy emitter incommunication with the bone fill material injector system, andelectronically controlling the delivery of energy to the thermal energyemitter to achieve a desired bone fill material viscosity based at leastin part on a sensed pressure in the bone fill material injector system.

In accordance with still another embodiment, a bone treatment system isprovided. The system comprises a handle component in communication withone or more energy sources, and a sleeve component having a proximalportion attached to the handle component and a distal end configured forpositioning in a bone, the handle and sleeve components defining a flowchannel extending therethrough. The system also comprises a first energyemitter configured for delivering energy to a bone fill material flow ina flow channel portion in the handle component, and a second energyemitter configured for delivering energy to a bone fill material flow ina flow channel portion in the sleeve component.

In accordance with yet another embodiment, a method for treating a boneis provided. The method comprises inserting at least a portion of aninjector of a bone cement injector system within a vertebral body,providing a flow of a settable bone cement having a first viscosity intoa proximal portion of the injector, and applying energy to the bonecement via a thermal energy emitter of the bone cement injector systemto cause the viscosity of the bone cement to change from the firstviscosity to a second viscosity, different than the first viscosity. Themethod also comprises urging the bone cement having the second viscosityfrom the proximal portion toward the distal portion of the injector,applying energy to the bone cement via another thermal energy emitter ofthe bone cement injector system disposed within the injector to causethe flow of bone cement exiting an outlet of the injector to achieve athird viscosity, different than the first and second viscosities, andintroducing the bone cement with said third viscosity into cancellousbone.

These and other objects of the present invention will become readilyapparent upon further review of the following drawings andspecification.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand embodiments of the present disclosure andto see how they may be carried out in practice, selected embodiments arenext described, by way of non-limiting examples only, with reference tothe accompanying drawings, in which like reference characters denotecorresponding features consistently throughout similar embodiments inthe attached drawings.

FIG. 1 is a perspective view of a bone cement injection system inaccordance with one embodiment of the present disclosure;

FIG. 2 is another view of the system of FIG. 1 with the bone cementinjection components de-mated from one another;

FIG. 3 is an embodiment of a thermal emitter component of the system ofFIGS. 1 and 2;

FIG. 4 is another view of the components of the system of FIGS. 1-2together with an embodiment of a pressurization mechanism and blockdiagram of an embodiment of an energy source and controller;

FIG. 5 is an enlarged, assembled view of several components of thesystem of FIG. 4;

FIG. 6 is a perspective view of components of the system of FIGS. 1-5with a perspective view of one embodiment of an energy source andcontroller.

FIG. 7 is chart indicating a time-viscosity curve for a prior art PMMAbone cement;

FIG. 8A is chart indicating a time-viscosity curve for an embodiment ofa PMMA bone cement of the present disclosure;

FIG. 8B is chart indicating a modified time-viscosity curve for the PMMAbone cement of FIG. 8A when modified by energy applied from anembodiment of a thermal energy emitter and a selected energy-deliveryalgorithm according to the present disclosure;

FIG. 9A is chart indicating another modified time-viscosity curve forthe PMMA bone cement of FIG. 8A when modified by applied energy and analternative energy-delivery algorithm;

FIG. 9B is chart indicating another modified time-viscosity curve for aPMMA bone cement when modified by applied energy and an alternativeenergy-delivery algorithm;

FIG. 10 is chart indicating time-viscosity curves for an embodiment ofthe PMMA bone cement as in FIG. 8A at different ambient temperatures;and

FIG. 11 is a view of another embodiment of a bone cement injectionsystem with components de-mated from one another, where the systemincludes first and second thermal energy emitters.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the embodiments illustrated in thedrawings and accompanying text. As background, a vertebroplastyprocedure using embodiments of the present disclosure would introducethe injector of FIGS. 1-2 through a pedicle of a vertebra, or in aparapedicular approach, for accessing the osteoporotic cancellous bone.The initial aspects of the procedure are similar to a conventionalpercutaneous vertebroplasty where the patient is placed in a proneposition on an operating table. The patient is typically under conscioussedation, although general anesthesia is an alternative. The physicianinjects a local anesthetic (e.g., 1% Lidocaine) into the regionoverlying the targeted pedicle or pedicles as well as the periosteum ofthe pedicle(s). Thereafter, the physician uses a scalpel to make a 1 to5 mm skin incision over each targeted pedicle. Thereafter, the bonecement injector is advanced through the pedicle into the anterior regionof the vertebral body, which typically is the region of greatestcompression and fracture. The physician confirms the introducer pathposterior to the pedicle, through the pedicle and within the vertebralbody by anteroposterior and lateral X-Ray projection fluoroscopic views.The introduction of infill material, as described below, can be imagedseveral times, or continuously, during the treatment depending on theimaging method.

The terms “bone cement, bone fill or fill material, infill material orcomposition” includes its ordinary meaning as known to those skilled inthe art and may include any material for infilling a bone that includesan in-situ hardenable or settable cement, or a composition that can beinfused with such a hardenable cement. The fill material also caninclude other “fillers” including, but not limited to, filaments,microspheres, powders, granular elements, flakes, chips, tubules and thelike, autograft or allograft materials, as well as other chemicals,pharmacological agents or other bioactive agents.

The term “flowable material” includes its ordinary meaning as known tothose skilled in the art and may include a material continuum that isunable to withstand a static shear stress and responds with anirrecoverable flow (e.g., a fluid), unlike an elastic material orelastomer that responds to shear stress with a recoverable deformation.Flowable material includes fill materials or composites that include afirst component (e.g., a fluid) and a second component that may includean elastic or inelastic material component that responds to stress witha flow, no matter the proportions of the first and second component, andwhere the above shear test does not apply to the second component alone.

The terms “substantially” or “substantial” mean largely but notentirely. For example, substantially may mean about 50% to about99.999%, about 80% to about 99.999% or about 90% to about 99.999%.

The term “vertebroplasty” includes its ordinary meaning as known tothose skilled in the art and may include any procedure wherein fillmaterial is delivered into the interior of a vertebra.

The term “cancellous bone”, also known as “spongy bone” includes itsordinary meaning as known to those skilled in the art and may include aporous bone having a honeycombed or spongy appearance that enclosesnaturally occurring, pre-existing spaces filled with bone marrow, thehoneycomb-like structure organized into a three-dimensional matrix orlattice of bony processes, called trabeculae, arranged along lines ofstress.

The term “cortical bone”, also known as “compact bone” includes itsordinary meaning as known to those skilled in the art and includes thedense outer surface of bones that forms a protective layer around theinternal bone including cancellous bone.

The term “osteoplasty” includes its ordinary meaning as known to thoseskilled in the art and may include any procedure wherein fill materialis delivered into the interior of a bone.

In FIG. 1, a system 10 is shown that includes a first component, or bonecement injector, 100 a distal end 120 of which can extend into thecancellous bone portion of a vertebra, and a second component, or cementactivation component, 105 which includes an emitter 110 for applyingenergy to bone cement. The first and second components 100 and 105include a flow passageway, or channel, 112 extending therethrough fordelivering a flowable bone cement into a bone. In certain embodiments,the bone cement injector component 100 and the cement activationcomponent 105 can be integrated into a unitary device (e.g., a singlepiece). In other embodiments, the bone cement injector component 100 andthe cement activation component 105 can be de-mateable, as shown in FIG.2, by a coupling mechanism such as threaded portion 113 and rotatablescrew-on fitting 114. As can be seen in FIGS. 1 and 2, a source of bonecement in the form of a syringe-type body 115 can also be coupled to thesystem by a coupling mechanism such as a threaded fitting 116.

Referring to FIG. 2, the bone cement injector 100 has proximal end 118and distal end 120 with at least one flow outlet 122 to direct a flow ofcement into a bone (e.g., a vertebra) so that the bone cementinterdigitates with cancellous bone (e.g., flows throughnaturally-occurring pre-existing openings in cancellous bone). Theextension portion 124 of the injector 100 may be a sleeve with flowpassageway 112 extending therethrough to the flow outlet 122. In anembodiment, the flow outlet 122 can include a side port that directscement flow transversely relative to the axis 125 of extension portion124. In another embodiment, the flow outlet 122 can be positioned atabout the distal termination of extension portion 124 in order to directcement flows distally. In another embodiment (not shown) the extensionportion 124 can include first and second concentric sleeves having firstand second flow outlets, respectively, that can be rotated relative toone another in order to align or misalign the first and second flowoutlets to allow selectively directed cements flow to be more or lessaxial relative to axis 125 of extension portion 124. The extensionportion may further be constructed of any suitable metal or plastic.

Now turning to the cut-away view of FIG. 2, it can be seen that thesecond component 105 can include a handle portion that carries anemitter 110 for applying thermal energy to a cement flow within flowchannel 112 that extends through the emitter 110. As will be describedfurther below, the emitter 110 can be operated to apply thermal energyto bone cement 130 delivered from chamber 132 of source 115 to flowthrough the emitter 110 to therein to provide “on-demand” a selectedhigher viscosity cement as the cement exits the injector flow outlet 122into bone. The controlled application of energy to bone cement 130allows the physician to advantageously select a setting rate for thecement to reach a selected polymerization endpoint as the cement isbeing introduced into the vertebra, thus allowing a high viscosity thatwill be prevent unwanted cement extravasation.

Referring to FIGS. 2 and 3, in one embodiment, the thermal energyemitter 110 is coupled to electrical source 140 and controller 145 by aelectrical connector 146 and cable 148. In FIG. 2, it can be seen thatelectrical leads 149 a and 149 b couple with connector 146 and extendand electrically connect to the emitter 110. As can be seen in FIG. 3,one embodiment of thermal energy emitter 110 has a wall portion 150 thatcomprises a polymeric positive temperature coefficient of resistance(PTCR) material with spaced apart interlaced surface electrodes 155A and155B as described in co-pending Provisional Application No. 60/907,468filed Apr. 3, 2007 titled Bone Treatment Systems and Methods. In thisembodiment, the thermal emitter 110 and wall 150 thereof willresistively heat to thereby cause controlled thermal effects in bonecement 130 flowing therethrough. It should be appreciated that FIG. 3 isa schematic representation of one embodiment of thermal energy emitter110 which can have any elongated or truncated shape or geometry, taperedor non-tapered form, or comprise the wall of a collapsible thin-wallelement. Further, the positive (+) and negative (−) polarity electrodes155A and 155B can have any spaced apart arrangement, for exampleradially spaced apart, helically spaced apart, axially spaced apart orany combination thereof. This resistively heated PTCR material of theemitter 110 may further generate a signal that indicates flow rate asdescribed in Provisional Application No. 60/907,468, which in turn canbe utilized by controller 145 to modulate energy applied to the bonecement therein, and/or modulate the flow rate of cement 130 which can bedriven by a motor or stored energy mechanism. In another embodiment, theemitter can be any non-PTCR resistive heater such as a resistive coilheater. However, the emitter 110 can have other suitable configurations.

In other embodiments, the thermal energy emitter 110 can be a PTCRconstant temperature heater as described above or selected from thegroup of emitters consisting of at least one of a resistive heater, afiber optic emitter, a light channel, an ultrasound transducer, anelectrode and an antenna. Accordingly in any such embodiment, the energysource 140 can comprise at least one of a voltage source, aradiofrequency source, an electromagnetic energy source, a non-coherentlight source, a laser source, an LED source, a microwave source, amagnetic source and an ultrasound source that is operatively coupled tothe emitter 110.

Referring FIG. 2, it can be understood that a pressure source orpressure mechanism 190 is coupleable to the bone cement source orsyringe 115 for driving the bone cement 130 through the system 10. Thepressure source 190 can be any suitable manual drive system or anautomated electrically driven system such as any pump (e.g., motordriven pump), screw drive, pneumatic drive, hydraulic drive, cable driveor the like. Such automated drive systems can be coupled to thecontroller 145 to modulate the flow rate or pressure of cement throughthe system.

In one embodiment shown in FIGS. 4-6, the pressure source 190 includes ahydraulic system 162 with a fitting 163 that may detachably couple to afitting 164 of the bone cement source 115. In this embodiment, the bonecement source 115 includes a syringe body with cement-carrying bore orchamber 132 that carries a pre-polymerized, partially polymerized orrecently-mixed bone cement 130 therein. The hydraulic system 162 canfurther include a rigid plunger or actuator member 175 with o-ring orrubber head 176 that can move in chamber 132 to push the cement 130through the syringe chamber 132 and the flow channel 112 in the system100.

Still referring to FIGS. 4-6, a force application and amplificationcomponent 180 of the hydraulic system 162 can be de-mateably coupled tothe bone cement source 115, where the component 180 includes a body 182with a pressurizable bore or chamber 185 that slidably receives theproximal end 186 of an actuator member 175. The proximal end 186 of theactuator member 175 includes an o-ring or gasket 187 so that the bore185 can be pressurized with flow media 188 by the pressurizing mechanism190 to drive the actuator member 175 distally to thereby displace bonecement 130 from chamber 132 in the cement source or syringe 115.

In one embodiment, the surface area of an interface 200 between theactuator member 175 and pressurized flow media 188 is substantiallylarger than the surface area of an interface 200′ between the actuatormember 175 and bone cement 130 to thereby provide pressure amplificationbetween the pressurizable chamber 185 and chamber 132 of the cementsource or syringe. In one embodiment as indicated in FIGS. 4 and 5, thesurface area of interface 200 is at least 150% of the surface area ofinterface 200′, at least 200% of the surface area of interface 200′, atleast 250% of the surface area of interface 200′, and at least 300% ofthe surface area of interface 200′.

Referring to FIGS. 4 and 5, in one embodiment, a force amplificationmethod of the present disclosure includes: (a) providing a bone fillmaterial injector with a displaceable non-fluid actuator componentintermediate a first fluid chamber and a second cement or fill-carryingchamber; (b) causing a flow of flow media at a first pressure into thefirst fluid chamber thereby displacing the actuator component to impingeon and eject bone cement or fill at a higher second pressure from thesecond chamber into a vertebra. The method provides a second pressure inthe cement-carrying chamber 165 that is: at least 50% higher that thefirst pressure in the pressurizable chamber 185, at least 50% higherthat the first pressure in the pressurizable chamber 185, at least 100%higher that the first pressure in the pressurizable chamber 185, atleast 200% higher that the first pressure in the pressurizable chamber185, at least 300% higher that the first pressure in the pressurizablechamber 185.

Referring to FIGS. 5 and 6, one embodiment of pressurizing system 190includes a pneumatic or hydraulic line 205 that extends to pressurizingmechanism that can include a syringe pump 210 that is manually driven ormotor-driven, (e.g., electrically driven), as is known in the art. Inone embodiment as shown in FIG. 6, the syringe pump 210 is driven by anelectric motor 211 operatively coupled to controller 145 to allowmodulation of the pressure or driving force in combination with thecontrol of energy delivery by the emitter 110 from the energy source140. It should be appreciated that the pressurizing mechanism 210 can beany type of mechanism or pump known in the art to actuate the actuatormember 175 to move the bone cement in chamber 165. For example, asuitable mechanism can be a piezoelectric element for pumping fluid, anultrasonic pump element, a compressed air system for creating pressure,a compressed gas cartridge for creating pressure, an electromagneticpump for creating pressure, an air-hammer system for creating pressure,a mechanism for capturing forces from a phase change in a fluid media, aspring mechanism for releaseably storing energy, a spring mechanism anda ratchet, a fluid flow system and a valve, a screw pump, a peristalticpump, a diaphragm pump, or any rotodynamic pumps or any positivedisplacement pumps.

FIG. 6 also shows another feature of certain embodiments of the presentdisclosure, namely a remote switch 212 for actuating the pressurizingmechanism 190 as well as delivery of energy from the energy source 140to the emitter 110. In one embodiment, a cable 214 extends from thecontroller 145 to the switch 212 so that the physician canadvantageously stand outside or the radiation field created by anyimaging system used while treating a vertebra or other bone treatmentsite. In another embodiment, the switch 212 can be wirelessly connectedto the system as is known in the art. In another embodiment (not shown),the elongated cable 214 and switch 212 can be directly coupled to theinjector or other components of the system.

In one embodiment, the bone treatment system includes a bone cementinjector system including a thermal energy emitter 110 for deliveringenergy to the bone cement in the injector system, a controller 145 formodulating applied energy from the emitter to thereby control a curingreaction of the cement, and a sensor system operatively coupled to theinjector system for measuring an operational parameter of bone cementwithin the system. In FIG. 6, in one embodiment, it can be seen that onesensor of the sensor system can include an ambient temperature sensorindicated at 270 which can be disposed in the controller assembly 140.The ambient temperature sensor 270 in the controller assembly 140 canallow for ambient temperature input into the system control algorithmsfor modulating applied energy from the emitter 110 based at least inpart on ambient air temperature in the operating room environment, whichcan affect the time-viscosity curve of an exothermic PMMA bone cement.

In another embodiment, referring to FIG. 6, the system can include atemperature sensor 272 disposed in a mixing device or assembly 275 whichcan be any container that receives the bone cement precursors for mixingbefore placement of the mixed cement in the bone cement source 115 (seeFIG. 6). It is useful to have a temperature sensor 272 in the cementmixing assembly because cement may be stored in a hospital in anenvironment having a lower or higher temperature than the operating roomwhich also will affect the time-viscosity curve of the cement. Thetemperature sensor 272 can be operatively coupled to the controller by acable or a wireless transmitter system. The sensor 272 can be unitarywith the mixing assembly and disposable in one embodiment, or can bereusable and/or detachable from the mixing assembly 275 in anotherembodiment. In another embodiment, still referring to FIG. 6, atemperature sensor 276 can be operatively connected to one or morepackages 280 of the bone cement precursors to thereby indicate theactual temperature of the cement precursor(s) prior to mixing, whichwill indicate the stored temperature and/or the length of time that suchcement precursors have been in the operating room when compared to anambient room temperature measured by sensor 270. In one embodiment, thesensor 276 can be a thermocouple or a thermochromic ink on the packagingthat allows for visual identification of the temperature of the cementprecursors for input of such temperature into the controller 145 toallow for automatic adjustment of the energy delivery algorithms ofembodiments of the present disclosure based at least in part on thesensed temperature from the sensor 276. In another embodiment, referringback to FIG. 4, at least one temperature sensor 282 can be located in oron the cement source 115 of the system and/or in a distal portion of theinjector component 100 for monitoring cement temperature in a cementflow within the system 10.

In another embodiment, the bone cement system and more particularly thecement mixing assembly 275 of FIG. 6 can include a sensor, switch, orindication mechanism 285 for indicating the time of initiation of bonecement mixing. Such a sensor or indication mechanism 285 can be anymanually-actuated mechanism coupled to the controller or a mechanismthat senses (e.g., automatically) the disposition of the cementprecursors in the mixing assembly or the actuation of any moveablemixing component of the assembly. The system and controller 145 then canprovide a visual, aural, or tactile signal indicating that apre-determined mixing time interval has been reached, which will thusassure that a time zero post-mixing viscosity will be similar in allcases to thereby allow optimal applied energy as described above. Thesystem also can include a sensor, switch, or indication mechanism 288that indicates the termination of bone cement mixing, and thus time zeroon a time-viscosity curve as discussed in detail with respect to FIG. 9,which is needed for setting the algorithms in the controller 145 forcontrolling applied energy and the cement flow rate.

In another embodiment, the bone cement system 10 includes a sensor thatmeasures and indicates the bone cement flow rate within the flowpassageway in the injector system. In the embodiment of FIG. 6, themotor drive system 211 may drive the cement via the hydraulic system atan approximately constant rate through the injector and emitter 110. Forexample, in one embodiment, a sensor 290 may be operatively coupled tothe motor drive which can measure the force and/or pressure beingapplied by the drive to cause the desired cement flow through thesystem. This force measurement, in turn, may be used to sense anytendency for a slow-down in the desired flow rate, for example due to anunanticipated increase in viscosity of cement in the system. Uponsensing such an increase, the controller 145 can increase the flow rate(e.g., increase the drive pressure) or decrease the applied energy fromemitter 110 to attain the desired cement viscosity and flow rate fromthe injector 100 into bone. Likewise, upon sensing a tendency for anincrease in the desired flow rate, such as an unanticipated decrease inviscosity of the cement, the controller 145 can increase the flow rate(e.g., increase the drive pressure) or increase the applied energy fromemitter 110 to ensure the desired cement viscosity and flow rate fromthe injector 100 into the bone is attained.

In further embodiments, one or more of the sensors 270, 272, 276, 282,285, 288, 290 may be in communication with the controller 145 for inputof data collected by the sensors into the controller 145. For example,in certain embodiments, an operator may obtain at least a portion of thedata collected by the sensors 270, 272, 276, 282, 285, 288, 290 andmanually input the relevant data into the controller 145. In alternativeembodiments, one or more of the sensors 270, 272, 276, 282, 285, 288,290 may possess a direct connection, such as a wired or wireless dataconnection with the controller 145, whereby the controller 145 mayrequest data from the sensors 270, 272, 276, 282, 285, 288, 290 and/orthe sensors 270, 272, 276, 282, 285, 288, 290 may communicate at least aportion of collected data to the controller 145.

Now turning to FIGS. 7, 8A, and 8B, charts are presented that illustratecertain aspects of embodiments of methods for controlled application ofenergy to a bone cement 130 provide a cement with a controlled,on-demand increased viscosity and a controlled set time, as compared toa prior art bone cement. FIG. 7 depicts a prior art bone cement known inthe art, such as a PMMA bone cement, that has a time-viscosity curve 240where the cement substantially hardens or cures within about 8 to 10minutes, post-mixing. On the horizontal axis of FIGS. 7, 8A, and 8B, thetime point zero indicates the time at which the mixing of bone cementprecursors (typically the monomer and polymer components) issubstantially completed. As can be seen in the prior art bone cement ofFIG. 7, the cement increases in viscosity from about 500 Pa·s to about750 Pa·s from time zero to about 6 minutes, post-mixing. Thereafter, thecement viscosity increases very rapidly over the time interval fromabout 6 minutes to 8 minutes post-mixing to a viscosity greater than4000 Pa·s. A prior art bone cement having the time-viscosity curve ofFIG. 7 may be considered to have a fairly high viscosity for injectionin the range of about 500 Pa·s. At this viscosity range, however, thebone cement can still possess flow characteristics that result inextravasation.

Still referring to FIG. 7, it can be further understood that the “curingreaction”, also referred to herein as a cement curing source is anexothermic chemical reaction that initiates a pre-determinedpolymerization process that is primarily dictated by the composition andconcentration of the bone cement precursors, such as the PMMA polymer,monomer, and initiator. FIG. 7 indicates the exothermic curing reactionover time as a gradation where the lighter gradation region indicates arelatively lower degree of chemical reaction and heat and the darkergradation region indicates a relatively higher degree of chemicalreaction and heat leading to more rapid polymerization of the bonecement precursors.

Now turning to FIG. 8A, the time-viscosity curve 250 of one embodimentof a bone cement is shown, where the initial viscosity of the bonecement is in the range of about 750 Pa·s at approximately time zeropost-mixing. Subsequently, the viscosity increases in a more linearmanner over about 10 to 14 minutes post-mixing than is observed in priorart bone cements. This embodiment of bone cement can be a PMMA cementcomposition that provides a time-viscosity curve as in FIG. 8A, and ismore particularly described in U.S. Provisional Application No.60/899,487 filed on Feb. 5, 2007, titled Bone Treatment Systems andMethods, and U.S. patent application Ser. No. 12/024,969 filed Feb. 1,2008, titled Bone Treatment Systems and Methods, each of which isincorporated herein by this reference in their entirety and should beconsidered a part of this specification.

As can be seen in FIG. 8A, the bone cement 130, or more particularly,the mixture of cement precursors, includes a first cement curing sourcefor curing the bone cement that yields a predetermined curing responsepost-mixing that is indicated by the gradations of reaction under thetime-viscosity curve 250. In certain embodiments, the first cementcuring source may include the exothermic curing reaction describedabove. FIG. 8A illustrates an embodiment of the curing response obtainedfrom the chemical curing reaction graphically, with gradation region 252being the initiation of the chemical reaction, gradation region 252′being the peak of the chemical reaction and gradation region 252″ beinga diminishing portion of the chemical reaction with the correspondingincrease in viscosity indicated on the vertical axis.

Now turning to FIG. 8B, another chart illustrates the same PMMA bonecement of FIG. 8A with time-viscosity curve 250 together with a modifiedtime-viscosity curve 260 that is provided by a second cement curingsource. In an embodiment, the second cement curing source can includeenergy applied to the bone cement 130 according to embodiments of system100 disclosed herein, as depicted in FIGS. 1 and 4-6, which modifies thetime viscosity curve 250 to yield modified time-viscosity curve 260.

Thus, FIG. 8B illustrates one embodiment of the disclosure where thefirst curing reaction of the bone cement (i.e., the time-viscosity curve250) is combined with the second curing reaction contributed by theapplied energy from energy source 140, controller 145, and emitter 110to provide the “modified” or “controlled” time-viscosity curve 260 forcement injection into a bone for preventing extravasation. As can beunderstood from FIG. 8B, the modulation of applied energy over time fromthe second curing source or emitter 110, indicated schematically atenergy applications E, E′, E″, and E′″, can be provided to complementthe varied energy from the first curing source (exothermic reaction) toprovide a substantially constant cement viscosity over a selectedworking time.

This aspect of the invention allows, for the first time, a controlledand substantially constant viscosity cement at a selected viscositylevel that is selected to inhibit (e.g., prevent) extravasation. Thisaspect of the inventive bone cement 130 and system 10 is advantageous inthat a typical treatment of a vertebral compression fracture requirescement injection over a period of several minutes, for example fromabout 2 to 10 minutes, about 2 to 6 minutes, or about 2 to 4 minutes.The physician typically injects a small amount of bone cement, forexample about 1 or 2 cc's, then pauses cement injection in order toimage the injected cement to check for extravasation, then repeats theadditional cement injection and imaging operations as necessary. Forexample, in a non-limiting embodiment, the injection and imagingoperations may be repeated from about 2 to 10 times or more, where thecomplete treatment interval can take about 4 to 6 minutes or more. Itcan be easily understood that a cement with a working time of at leastabout 5-6 minutes is needed for a typical treatment of a VCF, otherwisethe first batch of cement would be too advanced in the curing process(see FIG. 7) and a second batch of cement would need to be mixed. In thecement 130 and system 10 indicated in FIG. 8B, the cement viscosity canbe approximately constant, thus providing a very long working time ofabout 8-10 minutes. It should be appreciated that, in the chart of FIG.8B, the first and second curing reactions and applied energy areindicated by shaded areas below curves 250 and 260. This graphicrepresentation is for conceptual purposes only, as the vertical axismeasures viscosity in Pa·s. The actual applied energy indicated at E toE′″ is determined by analysis of the actual polymerization reaction timeof a selected bone cement composition at selected operating parametersthat may include, but are not limited to, ambient temperature, bonecement storage temperature, bone cement temperature during and/or aftermixing, atmospheric pressure, and controller motor drive pressure (e.g.pressure measured by sensor 290). Viscosity-time profile 260 may beadvantageous under circumstances where injecting a bone cement having agenerally uniform stiffness throughout the volume of the injected bonecement is desired.

With continued reference to FIG. 8B, the system and method provide acontroller 145 and energy emitter 110 that can apply energy sufficientto very rapidly increase the viscosity of bone cement to a selectedviscosity that will not allow for extravasation. As can be seen in FIG.8B, the time-viscosity curve 260 within about 15-30 seconds can beelevated to above about 2000 Pa·s. The method of bone cement treatmentencompasses utilizing an energy emitter 110 that applies energy to bonecement to controllably increase its viscosity in less than about 2minutes or less than about 1 minute by at least 200 Pa·s, at least 500Pa·s or at least 1,000 Pa·s. Alternatively, the method of bone cementtreatment encompasses utilizing an energy emitter that applies energy tobone cement to controllably increase the viscosity in less than 2minutes or less than 1 minute to at least 1,000 Pa·s, at least 1,500Pa·s, at least 2,000 Pa·s, at least 2,500 Pa·s, at least 4,000 Pa·s, orat least about 5,000 Pa·s.

Thus, in one embodiment of the present disclosure, the bone cementsystem includes: first and second sources for causing a controlledcuring reaction in a bone cement, where the first source includes apredetermined exothermic curing reaction in response to mixing cementprecursor compositions and the second source includes a thermal energyemitter 110 for providing a variable curing reaction in the cement, anda controller 145 for modulating applied energy from the thermal energyemitter 110 to thereby control the curing reaction over a selectedworking time.

It can be understood from co-pending U.S. Provisional Application No.60/899,487 filed on Feb. 5, 2007, titled Bone Treatment Systems andMethods and U.S. patent application Ser. No. 12/024,969 filed Feb. 1,2008, titled Bone Treatment Systems and Methods, that PMMA cementcompositions can be created to provide highly-extended working times.Such bone cements in combination with the system 10 of embodiments ofthe present disclosure thus allow for selected working times of at least6 minutes, 8 minutes, 10 minutes, 12 minutes, 14 minutes, 16 minutes, 18minutes, 20 minutes, 25 minutes. Further embodiments provide a controlsystem that allows for providing a bone cement within a selected cementviscosity range as it exits the injector outlet 122 over the selectedworking time. Further embodiments provide a controller that is capableof providing a substantially constant cement viscosity over the selectedworking time. Additional embodiments provide a controller that iscapable of providing a plurality of selected time-viscosity profiles ofthe cement as it exits the injector.

In one embodiment of the present disclosure, the bone cement systemincludes: first and second sources for causing a controlled curingreaction in a bone cement, where the first source includes apredetermined exothermic curing reaction in response to mixing cementprecursor compositions and the second source includes thermal energyapplied to the bone cement from an external source, and a control systemthat controls the thermal energy applied by the external source so as toprovide a cement exiting the injector a selected viscosity of at least600 Pa·s, 800 Pa·s, 1000 Pa·s, 1200 Pa·s, 1400 Pa·s, 1600 Pa·s, 1800Pa·s, 2000 Pa·s, 2500 Pa·s, 3000 Pa·s, 4000 Pa·s, or at least 5,000Pa·s.

In another embodiment, the present disclosure provides a method ofpreparing a curable bone cement for injection into a vertebra. Themethod includes mixing bone cement precursors such that a firstnon-variable curing reaction occurs between the precursors in the bonecement and applying energy to the bone cement from an external source toprovide a second variable curing reaction in the bone cement, whereinapplied energy from the second source is controlled by a controller topermit a combination non-variable and variable curing reaction therebyproviding a selected cement viscosity. Further, the method includesvarying the applied energy from the second source in response to thelength of a post-mixing interval. Further, the method includes varyingthe applied energy from the second source in response to ambienttemperature that is measured by a temperature sensor in the system.Further, the method includes varying the applied energy from the secondsource in response to a selected injection rate of the bone cement flowthrough the system. Further, the method includes varying the appliedenergy from the second source to provide a bone cement having aninjection viscosity of at least 500 Pa·s, 1000 Pa·s, 1500 Pa·s, 2000Pa·s, 3000 Pa·s, 4000 Pa·s or 5000 Pa·s.

In another embodiment, the present disclosure provides a method ofpreparing a curable bone cement for injection into a vertebra thatincludes mixing bone cement precursors thereby causing a first curingreaction characterizing the cement with a first time-viscosity profile,and actuating a controller to controllably apply energy to the bonecement from an external source, thereby modifying the firsttime-viscosity profile to a second time-viscosity profile, and injectingthe cement having the second time-viscosity profile into the vertebra.In this method, the cement viscosity is at least 500 Pascals-second,1000 Pa·s, 1500 Pa·s, 2000 Pa·s, 3000 Pa·s, 4000 Pa·s or at least 5000Pa·s. The method includes actuating the controller to modulate appliedenergy in response to control signals selected from the group consistingof the length of a cement post-mixing interval, ambient temperature,cement temperature, and rate of cement injection.

As can be understood from FIG. 8B and the description above, oneembodiment of the present disclosure allows for cement injection at aviscosity range of over 2500 Pa·s, which has been found to be beneficialfor substantially inhibiting extravasation of the cement. In oneembodiment, the bone treatment system can include a first source and asecond source for causing a controlled curing reaction in a bone cement,where the first source can be a predetermined exothermic curing reactionin response to mixing cement precursor compositions where the secondsource can be a thermal energy emitter for providing a variable curingreaction, and a controller for modulating applied energy from theemitter to thereby control the curing reaction over a selected workingtime. The controller can preferably modulate applied energy to provide aselected cement viscosity over a working time of at least 2 minutes, 4minutes, 6 minutes, 8 minutes, 10 minutes, 12 minutes, 14 minutes, 16minutes, 18 minutes, 20 minutes, or 25 minutes.

In another embodiment, a bone treatment system can include a bone cementinjector system, a thermal energy emitter for delivering energy to aflow of bone cement through the injector system and a controllerincluding an algorithm for modulating applied energy from the emitter toa bone cement flow, wherein the algorithm is increases the appliedenergy from zero at a rate selected to inhibit vaporization of monomerportions of the bone cement.

In another embodiment of the present disclosure, the controller 145allows for a physician to select a particular approximate cementviscosity by use of a selector mechanism operatively connected to thecontroller 145. In one embodiment, the physician can select among aplurality of substantially constant viscosities that can be deliveredover the working time, for example, a first choice may includeviscosities less than 1,000 Pa·s, and a second choice may includeviscosities in excess of 1,500 Pa·s. It should be appreciated that theselections can range from two to six or more, with each selection beinga viscosity range useful for a particular purpose.

In another embodiment of the present disclosure, referring to FIGS.9A-9B, the controller may also allow the physician to select anenergy-delivery algorithm in the controller 145 to provide a decrease incement viscosity following an initial upward spike in viscosity (curve260′) following the application of energy to the cement flow (FIG. 9A).It can be seen in FIG. 9A that energy delivery by emitter indicated at Eand E′ is terminated, resulting in the attained viscosity in subsequentportions of the cement flow to be reduced toward the baseline viscosityof the cement 250 provided by the exothermic reaction of the bone cementprecursors alone. Viscosity-time profile 260′ may be advantageous undercircumstances where injecting a bone cement having a relatively stiffouter surface (e.g., the portion of the bone cement having a relativelyhigh viscosity when energy E, E′ is applied) and a relatively less stiffinner core (e.g., the portion of the bone cement having viscosityreduced towards the baseline viscosity of cement 250) is desired.

Similarly, FIG. 9B indicates another energy-delivery algorithm whereinthe cement flow viscosity is modulated up and down within a viscosityrange indicated by time-viscosity curve 260″. In certain embodiments,the viscosity of the cement flow may be modulated about a mean value of1500 Pa·s, 2000 Pa·s, 3000 Pa·s, 4000 Pa·s and 5000 Pa·s, though otherviscosity mean values are possible. In other embodiments, the amplitudeof the modulated viscosity may be 50 Pa·s, 100 Pa·s, 500 Pa·s and 100Pa·s, though other amplitude values are possible. In another embodiment,the viscosity-time profile 260″ may arise under circumstances where theapplication of energy to the bone cement is controlled by the controller145 in accordance with pressure measured or sensed proximate thecontroller motor drive 211 (e.g., via sensor 290). For example, thecontroller 145 may attempt to maintain a target pressure. When sensor290 senses that the pressure exerted by the motor drive 211 increases ordecreases by greater than a selected amount from the target pressure,the controller may decrease or increase, respectively, the appliedenergy (e.g., energy applied by the thermal energy emitter 110 to bonecement 130) in order to cause the pressure to move back towards thetarget pressure. Because such a control system is feedback driven, theviscosity-time profile will tend to exhibit oscillations about thetarget pressure.

FIG. 10 provides a schematic graphical representation of the bone cementof FIG. 8A that, after mixing exhibits the time-viscosity curves 250 and255 corresponding to respective ambient temperatures of 22° C. and 18°C. It can be seen that different levels of applied energy would berequired to achieve a similar time-viscosity curve 260 of FIG. 10. Thus,in an embodiment of a treatment method of the present disclosure, inputsmay be provided to control algorithms for controlling applied energy tocement flows that factor in ambient temperatures.

In another embodiment, referring to FIG. 11, the bone cement system 400includes first and second thermal energy emitters 110 and 410 forcontrolled application of energy to a bone cement flow within the flowpassageway 112 of the injector system. More particularly, the firstemitter 110 is disposed in the first handle component 105 as describedpreviously. The second emitter 410 is disposed in a portion (e.g.,medial or distal) of the second extension component 110 of the system.The controller 145 can modulate applied energy from one or both of thefirst and second emitters 110 and 410 to provide a controlled curingreaction of the flow of bone cement 130. In one method of use, the firstemitter 110 can apply energy to heat the flow of the bone cement carriedto the location of the second emitter 410 at a viscosity of less thanabout 500 to 1000 Pa·s. This first bone cement heating can enable theviscosity of the bone cement within the flow channel 112 to be keptwithin a range that can be pushed through the bone cement injector 100with a low level of pressure. For example, the bone cement may be pushedthrough the injector 100 at pressures ranging between about 100 psi andabout 1500 psi. Thereafter, the second emitter 410 can apply energy toheat the flow of cement and accelerate its rate of polymerization so asto achieve a viscosity greater than 2000 Pa·s. Furthermore, in oneembodiment, the second emitter 110 may heat the bone cement such thatthe viscosity of bone cement exiting the outlet 122 can be at an evenhigher level, for example at a level capable of fracturing cancellousbone.

FIG. 11 further illustrates that electrical connector components 414 aand 414 b are provided in the interface between the first and secondcomponents, 105 and 110 to provide an electrical connection fromelectrical source 140 to the emitter 410 via electrical wires indicatedat 416 in the handle portion 105 of the system. It should be appreciatedthat the second emitter 410 can be a PTCR emitter, as describedpreviously, or any other type of heating element. The heating elementcan have any length including the entire length of the extension portion124.

In one embodiment of the system, the bone cement 130 has a predeterminedworking time for polymerizing from an initial state to a selectedendpoint of at least 10 minutes, 12 minutes, 14 minutes, 16 minutes, 18minutes, 20 minutes, 25 minutes, 30 minutes and 40 minutes, as disclosedin co-pending Provisional application Ser. No. 60/899,487 filed Feb. 5,2007 titled Bone Treatment Systems and Methods. In an embodiment, theselected endpoint may include providing the bone cement 130 in a partlypolymerized condition having a viscosity within a selected viscosityrange that substantially inhibits cement extravasation. In anon-limiting embodiment, extravasation may be inhibited when the bonecement viscosity is greater than about 2000 Pa·s.

The energy source 140 may accelerate a polymerization rate of the bonecement by at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 95% overthat which would be achieved absent application of energy to the bonecement from the energy source. In another embodiment, the energy source140 and controller 145 may accelerate the polymerization rate of thecement such that the selected endpoint of the bone cement is achieved inless than 1 second, 5 seconds, 10 seconds, 20 seconds, 30 seconds, 45seconds, 60 seconds and 2 minutes.

In an embodiment of a method of using the system 10 of FIGS. 1-6, themethod of treating a vertebra includes (i) introducing a cement injectorneedle into a vertebra, the needle having a flow channel extending froma proximal injector end to a distal injector end with a flow outlet,(ii) causing a flow of bone cement from the source through a flowchannel in the an energy-delivery component and the injector needle, and(iii) applying energy from the energy-delivery component to the flow tocause the bone cement to exhibit a different setting rate to reach aselected polymerization endpoint. In this method, the applied energyaccelerates setting of pre-polymerized bone cement before exiting theflow outlet. The method and the selected polymerization endpoint providea viscosity that substantially prevents cement extravasation followingintroduction into the vertebra.

In another embodiment of the method, the energy-delivery emitter 110 isactuated by the operator from a location outside any imaging field.

In a further embodiment of the method, the energy-delivery emitter 110may be actuated to apply energy of at least 0.01 Watt, 0.05 Watt, 0.10Watt, 0.50 Watt and 1.0 Watt. In another aspect of the method, theapplied energy is modulated by controller 145. In another aspect of themethod, the energy source and controller may accelerate thepolymerization rate of the bone cement to reach the selected endpoint inless than 1 second, 5 seconds, 10 seconds, 20 seconds, 30 seconds, 45seconds, 60 seconds and 2 minutes. In another aspect of the method, theenergy source and controller may accelerate the polymerization rate ofthe bone cement by at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and95%.

In another embodiment of the present disclosure, a method of bone cementinjection accordingly includes modulating the rate of cement flow inresponse to determining a selected parameter of the cement flow such asflow rate. The method of bone cement injection further included applyingand modulating thermal energy application from an emitter in theinjector body to the cement flow. The method of bone cement injectionfurther includes modulating the application of energy in response tosignals that relate to a selected parameter such as flow rate of thecement flow.

Of particular interest, another embodiment of a method of bone cementinjection includes (a) providing a bone cement injector body carrying aPTCR (positive temperature coefficient of resistance) material in a flowchannel therein, (b) applying a selected level of energy to a cementflow through the PTCR material, and (c) utilizing an algorithm thatprocesses impedance values of the PTCR material to determine the cementflow rate. The method of bone cement injection further includesmodulating a cement injection parameter in response to the processedimpedance values.

Another embodiment of a method of bone cement injection includes (a)providing a bone cement injector body carrying a PTCR material or otherthermal energy emitter in a flow channel therein, (b) causing a selectedcement flow rate and a selected level of energy delivery to the cementflow through the emitter, and (c) modulating the selected flow rateand/or energy delivery to maintain a substantially constant impedancevalue of the emitter material over a cement injection interval. Theselected cement injection interval can be at least 1 minute, at least 5minutes, at least 10 minutes and at least 15 minutes.

In another embodiment, of the method, the selected flow rate and/orenergy delivery may be modulated to maintain a substantially constantviscosity of bone cement ejected from the injector over a cementinjection interval. The system and energy source may apply energy of atleast 0.01 Watt, 0.05 Watt, 0.10 Watt, 0.50 Watt and 1.0 Watt. Inanother aspect, the energy source and controller may acceleratepolymerization rate of the bone cement to a selected endpoint in lessthan 1 second, 5 seconds, 10 seconds, 20 seconds, 30 seconds, 45seconds, 60 seconds and 2 minutes.

Another embodiment of a method of bone cement injection utilizes systemssuch as system 10 and 400 as described above and include (a) providing abone cement injector body with a flow channel extending therethroughfrom a proximal handle end though a medial portion to a distal endportion having a flow outlet, (b) causing cement flow through the flowchannel, and (c) warming the cement flow with an energy emitter in aproximal end or medial portion thereof to initiate or acceleratepolymerization of the cement of the cement flow. The method may furtherinclude providing a flow rate of the cement flow that ranges from 0.1cc/minute to 20 cc/minute, from 0.2 cc/minute to 10 cc/minute, and from0.5 cc/minute to 5 cc/minute.

Of particular interest, embodiments of the above-described methods ofbone cement injection provide delivery of bone cement at a predeterminedcement flow rate so as to allow cement flows a selected interval overwhich they are allowed to polymerize in the flow channel downstream fromthe energy emitter. This method includes providing a selected intervalof greater than 1 second, greater than 5 seconds, greater than 10seconds, greater than 20 seconds, and greater than 60 seconds.

The above-described method utilizes an energy emitter that appliesenergy sufficient to elevate the temperature of the bone cement by atleast 1° C., at least 2° C., and at least 5° C. The method of bonecement injection includes utilizing an energy emitter that applies atleast 0.1 Watt of energy to the cement flow, at least 0.5 Watt of energyto the cement flow, and at least 1.0 Watt of energy to the cement flow.The method includes the flow rate of the cement flow being adjusted inintervals by controller 145, or being continuously adjusted by acontroller.

The above disclosed embodiments are intended to be illustrative and notexhaustive. Particular characteristics, features, dimensions, and thelike that are presented in dependent claims can be combined and fallwithin the scope of the invention. The invention also encompassesembodiments as if dependent claims were alternatively written in amultiple dependent claim format with reference to other independentclaims. Specific characteristics and features of the invention and itsmethod are described in relation to some figures and not in others, andthis is for convenience only. While the principles of the invention havebeen made clear in the embodiments described above, it will be obviousto those skilled in the art that modifications may be utilized in thepractice of the invention, and otherwise, which are particularly adaptedto specific environments and operative requirements without departingfrom the principles of the invention. The appended claims are intendedto cover and embrace any and all such modifications, with the limitsonly of the true purview, spirit and scope of the invention.

Of course, the foregoing description is that of certain features,aspects and advantages of the present invention, to which variouschanges and modifications can be made without departing from the spiritand scope of the present invention. Moreover, the bone treatment systemsand methods need not feature all of the objects, advantages, featuresand aspects discussed above. Thus, for example, those skill in the artwill recognize that the invention can be embodied or carried out in amanner that achieves or optimizes one advantage or a group of advantagesas taught herein without necessarily achieving other objects oradvantages as may be taught or suggested herein. In addition, while anumber of variations of the invention have been shown and described indetail, other modifications and methods of use, which are within thescope of this invention, will be readily apparent to those of skill inthe art based upon this disclosure. It is contemplated that variouscombinations or sub-combinations of these specific features and aspectsof embodiments may be made and still fall within the scope of theinvention. Accordingly, it should be understood that various featuresand aspects of the disclosed embodiments can be combined with orsubstituted for one another in order to form varying modes of thediscussed bone treatment systems and methods.

What is claimed is:
 1. A method for treating a bone, comprising:inserting at least a portion of an injector of a bone cement injectorsystem within a vertebral body; providing a flow of a settable bonecement into a proximal portion of the injector; applying a firstnon-zero level of energy at a first time to the bone cement via one ormore thermal energy emitters of the bone cement injector system to causethe bone cement to change to a first viscosity, applying a secondnon-zero level of energy at a second time to the bone cement via the oneor more thermal energy emitters to cause the bone cement to change to asecond viscosity, wherein the first time is before the second time andthe first non-zero level of energy is unequal to the second non-zerolevel of energy, wherein the application of the first and secondnon-zero levels of energy is controlled based at least in part on asensed force applied to the bone cement injector system to modulate theviscosity of the bone cement between the first and second viscositiesabout a desired mean viscosity value; urging the bone cement from theproximal portion toward a distal portion of the injector; andintroducing the bone cement into cancellous bone of the vertebral body.2. The method of claim 1, wherein applying first and second non-zerolevels of energy to the bone cement comprises executing at least onealgorithm stored by a computer readable medium to controllably modulatethe levels of energy applied by at least one of the thermal energyemitters.
 3. The method of claim 2, wherein the at least one algorithmcomprises a plurality of preset algorithms.
 4. The method of claim 2,further comprising selecting an algorithm from a plurality ofalgorithms, the selected algorithm being one that causes the bone cementintroduced into the cancellous bone to interdigitate with the cancellousbone.
 5. The method of claim 4, wherein the first viscosity of the bonecement is at least 2000 Pa·s.
 6. The method of claim 1, wherein thedesired mean viscosity value is selected from the group consisting of1500 Pa·s, 2000 Pa·s, and 3000 Pa·s.
 7. The method of claim 1, whereinthe first viscosity is between 2500 Pa·s and 3000 Pa·s.
 8. The method ofclaim 1, wherein the second non-zero level of applied energy is lessthan the first non-zero level of applied energy.
 9. The method of claim1, further comprising delivering a third non-zero level of appliedenergy at a third time to cause the bone cement to change to the firstviscosity.
 10. The method of claim 9, further comprising delivering afourth non-zero level of applied energy at a fourth time to cause thebone cement to change to the second viscosity.
 11. A method for treatinga bone, comprising: flowing bone fill material through a bone fillmaterial injector system having at least a portion of an injectorpositioned in a cancellous bone portion of the bone; delivering a firstnon-zero level of applied energy to the flow of bone fill material via athermal energy emitter in communication with the bone fill materialinjector system, wherein delivering the first non-zero level of appliedenergy changes the viscosity of the bone fill material to a firstviscosity; delivering a second non-zero level of applied energy to theflow of bone fill material via the thermal energy emitter afterdelivering the first non-zero level of applied energy, whereindelivering the second non-zero level of applied energy changes theviscosity of the bone fill material to a second viscosity less than thefirst viscosity, the first and second viscosities defining a viscosityrange therebetween; delivering a third non-zero level of applied energyto the flow of bone fill material via the thermal energy emitter afterdelivering the second non-zero level of applied energy, whereindelivering the third non-zero level of applied energy changes theviscosity of the bone fill material to the first viscosity; wherein thethird non-zero level of applied energy is less than the first non-zerolevel of applied energy; and electronically controlling the delivery ofthe first, second, and third non-zero levels of energy via the thermalenergy emitter to modulate the viscosity of the bone fill material abouta desired mean bone fill material viscosity within the viscosity rangebased at least in part on a sensed parameter of the bone fill materialinjector system.
 12. The method of claim 11, further comprisingelectronically controlling a drive pressure of the bone fill materialflow through the injector system.
 13. The method of claim 12, whereinelectronically controlling one or both of the energy delivery and drivepressure comprises controlling one or both of energy delivery and drivepressure to achieve a mean viscosity within the viscosity range selectedfrom the group consisting of at least 1500 Pa·s, at least 2000 Pa·s, atleast 2500 Pa·s, at least 3000 Pa·s, at least 3500 Pa·s, at least 4000Pa·s, at least 4500 Pa·s, at least 5000 Pa·s, and greater than 5000Pa·s.
 14. The method of claim 11, wherein the second non-zero level ofapplied energy is less than the first non-zero level of applied energy.15. The method of claim 11, wherein desired mean bone fill materialviscosity is selected from the group consisting of 1500 Pa·s, 2000 Pa·s,and 3000 Pa·s.
 16. The method of claim 11, wherein an amplitude of themodulated viscosity is selected from the group consisting of 50 Pa·s,100 Pa·s, and 500 Pa·s.
 17. The method of claim 11, wherein the firstviscosity is between 2500 Pa·s and 3000 Pa·s.
 18. The method of claim11, wherein the first viscosity of the bone cement is at least 2000Pa·s.
 19. The method of claim 11, wherein applying first, second, andthird non-zero levels of energy comprises executing at least onealgorithm stored by a computer readable medium to controllably modulatethe levels of energy applied by at least one of the thermal energyemitters.
 20. The method of claim 19, wherein the at least one algorithmcomprises a plurality of preset algorithms.